We hand-delivered some of our invitations, one in particular to my cousins who live up the road from my parents' house. My sister dropped it off and it was on their counter when she left.
She went over there over the weekend--almost a month later--and the invitation was in the exact same spot, unopened! My cousin's wife was like, "What? You know we're coming." My sister said, "First, she needs your RSVP anyway. Second, don't you want to know the addresses where everything is?? And aren't you curious to know what the invitation looks like???" I thought that was so strange! Invites wouldn't last a day in my mail pile, let alone a month!